LOW-MOLECULAR-WEIGHT ORGANIC-ACIDS IN SELECTED FOREST SOILS OF THE SOUTHEASTERN USA

The low-molecular-weight aliphatic organic acids extracted in water and present in soil solution from O, A, Bh and Bt horizons from a group of forested Ultisols, Entisols and Spodosols were identified by high performance liquid chromatography (HPLC). Oxalic acid was found in all samples and was present generally in the highest concentrations. High concentrations of formic acid were also identified in most soils, ranging from 5 to 174 μM in soil solution. Trace amounts of citric, acetic, malic, lactic, aconitic, and succinic acids were detected in some samples. In a greenhouse pot study, the concentrations of low-molecular-weight organic acids in the rhizosphere of slash pine (Pinus elliottii Engelm.) seedlings growing in A, Bh, and Bt horizons from an Ultic Haplaquod were compared with the concentrations in the nonrhizosphere soil. The observed concentrations were approximately an order of magnitude greater than in native soils. -from Authors